Motor control system for regulating systems



Feb. 16, 1954 w. E. 'WRENN MOTOR CONTROL SYSTEM FOR REGULATING SYSTEMSFiled Nov. 7, 1951 4 Shets-Sheet 1 ilas INVENTOR illiom .Wrenn. BY

WITNESES:

Feb. 16, 1954 w. E. WRENN 2,669,680

MOTOR CONTROL SYSTEM FOR REGULATING SYSTEMS Filed Nov. '7, 1951 4Sheets-Sheet 3 Fig.3.

WITNESSES: INVENTOR 4 Sheets-Sheet 4 INVENTOR I & 4 0 8 m 0 l I v I 1 0A & 8 2 II I o 2 c 9. B .u 4 ,m w b 5 3 3 W. E. WREN N MOTOR CONTROLSYSTEM FOR REGULATING SYSTEMS Feb. 16, 1954 Filed Nov. 7

WITNESSES:

Patented Feb. 16, 1954 MOTOR CONTROL SYSTEM FOR REGULATING SYSTEMSWilliam E. Wrenn, Sharon, Pa., assignor to Westinghouse ElectricCorporation, East Pittsburgh, Pa., a corporation of PennsylvaniaApplication November 7, 1951, Serial No. 255,169

5 Qlaims.

This invention relates to electrical regulating systems, and inparticular to regulating systems utilizing a plurality of step typeregulators connected in parallel circuit relation for supplying a commonload.

Where a plurality of tap changing regulating transformers are connectedin parallel relation for supplying a common load, it is desirable thatsuch regulators be kept in step in order that circulating currentbetween the different tap changers will not cause excessive heating andreduce the output capacity of the regulating transformers. Differentsystems have been veloped heretofore in attempts to keep the regu latorsin step but they have had different operating disadvantages.

One of the main difiiculties has been in tlie braking of the tapchanging motors to cheat a positive braking and prevent an overrun ofthe parallel connected regulators associated with the motors with theresult that such overruns often are of such an extent as to result inforcing th regulators to an out-.ofestep position. Where the units arethus forced out of step, all ofthe units are usually locked out with theresult that the regulators cannot be further automati ally operateduntil the operator has acted to bring them back into step.

Further where braking is provided for each unit it is sometimes foundthat in the event of failure of one of the brakes or of the operating reassociated with the control of one of th motors, that one unit maycontinue to operate when the other is stopped with the result that suchone unit may be operated a number of steps out of parallel with respectto the other unit.

An object of this invention is to provide, in a regulating systemutilizing a plurality of step type regulators connected for paralleloperation,

them in step and interconnecting the braking controls for the motors toefiectively brake each of the motors upon the completion of a predetermined regulating operation of the associated regulator.

A further object is to provide, in a regulat-- 2 ing system utilizing aplurality of motor driven step type regulators connected for paralleloperation and having a brake associated with each of the motors foroperation after a regulating operation, an emergency brake for each ofthe motors having interconnected controls whereby the emergency brakesare operative to brake the motors if the normal brake fails to functionupon completion of a regulating operation to thereby maintain the unitsnot more than one step apart.

ther objects of this invention will become apparent from the followingdescription when taken in conjunction with the accompanying drawin s, inwhich:

Figures 1, 2, 3 and 4 form a composite drawing n Jigs. 1 and 2 aredisposed side by side and 3 and 4 are disposed side by side with theirupper edges butting the lower edges of Figs. 1 and 2, respectively, thecomposite drawing illustrating diagrammatically the circuits apparatusembodying the teachings of this invention.

Referring to the composite drawing, there is represented two regulatingunits and loci, being illustrated in block form and connected inparallel circuit relation for supplying a common load 42 from athree-phase alternating-current power system represented by theconductors l4, l8 and :8. Each of the units Ill and 59a is substantiallyidentical as to the components although the components of unit lea areinverted for the purpose of simplifying the connections between theunits in the drawing. For the purpose of simplifying the description ofthe components comprising the system illustrated, the components of unitIt! only will be described in detail, it being understood that likecomponents of unit Ira will be similarly identified by the number withthe suffix a appended thereto.

Each of the units includes a tap changing regulating transformer orregulator as having the primary windings thereof connected to besupplied from the conductors l4, l5 and 38. The secondary windings 22,24 and of the tap changing transformer are each provided with aplurality of taps 28 dispose. to be selectively engaged by a movablecontact member as positioned in response to operation of a suitablemotor operating mechanism represented by the motor 32. As illustrated,the secondary windings of the transformer 2c are connected by conductors3t, 35 and 33 to supply the load i2, the secondary windings beingprovided with a neutral point The motor operating or control syste forthe motor 32 is disposed to be connected by a three-pole switch 42having the switching members 4 3, 45 and 48 thereof for engaging fixedcontact members to connect the control system to conductors 34, 3t and aneutral conductor 55. which is connected to the neutral point 4G of thesecondary windings of the tap changing regulator.

In order to control the operation of the motor 32 in response to adeviation of the quantity which is to be regulated, a primary relay 52is illustrated as being connected through a potential transformer 54across the load conductor 34 and a neutral conductor 56 which isdisposed to be connected by the switch 48 to the conductor 59, wherebythe relay 52 will be energized to actuate its movable contact member 58into engagement with contact members 60 or 62 depending upon thedirection of the deviation. The primary relay 52 thus is disposed toinitiate the control of the operation of the motor 32 in one or theother directions by energizing one or the other of the time delay relays64 or 65 which, in turn, control secondary relays or contactors 68 orHi, respectively, the secondary relays being disposed to control theoperation of motor controlling relays or contactors I2 and I4,respectively, as will be described more fully hereinafter.

The motor 32 is of the split-phase capacitor type having twosubstantially identical singlephase windings I6 and I8 with aphase-shifting capacitor 80 disposed to be connected in series circuitwith one or the other of the windings 'IG and 18 and thus disposed whenenergized to control the directional operation of the motor 32. Asillustrated, the motor 32 is connected through a suitable gear drive(not shown) to operate the switch contact members 39 for simultaneouslyengaging the corresponding contact members 28 of the secondary windings22, 24 and 26 and,

simultaneously with a movement of the contact vmembers 3i), drive a pairof cam members 82 and 84 one revolution for each step of the movablecontact members 30. The cam members 82 and 84 are disposed to controlpredetermined switching operations.

Thus the cam 82, when the switch contact members 30 engage correspondingcontact members 28 of the secondary windings 22, 24 and 25, maintains acontact member 86 in a circuit interrupting position and a contactmember 88 in a circuit closing position. Upon a directional operation ofthe motor 32, the cam 82 is rotated to actuate contact member 86 to acircuit closing position and contact member 88 to a circuit interruptingposition.

The cam 84 is illustrated as a part of a motor driven switching unit 85and is disposed to drive a Geneva gear 9!! one-fourth of a revolutionfor each complete revolution of the cam 84 to drive cam members 92 and94 one-fourth of a revolution and control the positioning of contactmembers 96 and 98, respectively, the purpose of such contact membersbeing explained more fully hereinafter.

Associated with each of the control mechanisms is a master controller Ihaving contact members H12, I94. I06, I98 and llll disposed to givethree switching positions, identified as 1, 2 and 3, for selectivelyengaging cooperating fixed contact members depending upon which of thepositions the controller is actuated to. Thus with the controller I00 inswitching position 1 only contact members I04 and I08 engage thecorresponding fixed contact members; in position 2,

contact members I 02, me and we engage corresponding fixed contactmembers; and in position 3, contact members i632 and I It engagecorresponding fixed contact members. Positions 1, 2 and 3 may be termedthe follower, independent and master positions, respectively, suchpositions or setting of the controller I 09 being determined dependingupon whether it is desired to have the regulator unit with which thecontroller is associated operate as the master unit for all of the unitsconnected in parallel, or as a follower unit or as an independent unit.The controller 809 cooperates with the contact members 96 and 98 of theswitching unit 85 to control the operation of the regulating units whereone unit is the master unit and the other the follower as will beexplained more fully hereinafter.

In order to control the connection of the motor 32 to be initiallyenergized, a contactor i l2 having contact members lie and H6 isdisposed to be energized when one of the motor controller relays I2 andI4 is energized and an auxiliary braking relay H2 having contact membersI2i! and I22 is disposed to be energized when the control system isinitially energized. The auxiliary braking relay It in this instance isdisposed to control the encrgization of a time delay braking contactorI24 provided with a contact member I disposed to connect the terminalI28 of motor 32 to the switching member l so that the motor 32 isconditioned to be energized when one of the relays l2 and 1 isenergized.

In order to provide for braking the motor 32 upon completion of aregulating operation of the unit 29, a main braking relay 8'! having acontact member 89 is utilized and is disposed to cooperate with therelays i2 and 14 as disclosed in the copending application Serial No.192,503., filed October 27, 1950, in the name of McKeithan for shuntingthe capacitor 80 and connecting the windings I6 and 18 of the motor 32in parallel circuit relation as will be explained more fullyhereinafter.

An auxiliary controller I having contact members I32 and I34 is alsodisposed to cooperate with the controller I00 and a switch I36 when thecontroller is in No. 2 or independent position and the switch I is inthe open position for effecting independent manual adjustment of theassociated regulator as will be explained more fully hereinafter. Wherethe transformers 26 and 20a are connected in parallel to supply the loadI2 and it is desired to regulate their operation with one of the units,for example unit ID, as the master and unit Ida as the follower unit,the switches 42 and 42a and switches i36 and I351; are moved to circuitclosing positions and controller I00 of unit I0 is moved to the masterposition so that the contact members 32 and Iiil of position 3 engagetheir corresponding fixed contact members and controller Idea of unitIda is moved to the follower position 1 where the contact members 38aand Ma engage their corresponding fixed contact members. For suchautomatic operation the auxiliary controllers 530 and ltila. are in theopen circuit position illustrated. Assume that when such connections arefirst established the tap changing regulators 23 and 2641 are in stepand the system is in balance with the primary relay 52 in the neutralposition and cams 92 and 92a positioned as illustrated with theircontact members and 9611. respectively, in circuit closing position.

- If now the load I: should chan e so as to demend an operation of theregulating transiormer in a direction to increase the voltage, theprimary relays 52 and 52a are energized to actuate their movable contactmembers 58 and 58a,

re p c i y, into engagement with the fixed contact m mbers to and a,resp ctively. However, since the controller Iota is in the follower orNo, 1 position, the contact member IllZo does not bridge its associatedfixed contact members and the circuit to the movable contact member 58aremains open. On the other hand, the contact member I02 of thecontroller I80 establishes a circuit when the primary relay 52 isenergized, as described, which extends from the neutral c0nductorthrough the contact member I92, conductor I38, movable contact member 58and fixed contact member 50' of the primary relay 52, energizing windingI40 oi the time delay relay 54, conductor I42, switch I38, conductorsI44 and I48, contact member IIIl of'the controller I I00 and conductorI48 to the load conductor is.

When the time delay relay S4 is thus energized, its contact member I50is actuated to a circuit closing position provided such energize tion isof sufiicient duration to overcome the time delay characteristics of therelay. Thus, if the energization of relay 64 is only momentary. then thecontact member I50 remains in its open circuit position.

When the contact member 550 of time delay relay 64 is actuated to itscircuit closing position, a circuit is established which extends fromthe neutral conductor 56a of unit Illa through conductors I52 and IE4,contact member flea of the contactor II2a, conductor I 56, contactmember 96a of the switching unit 85a, conductor I58, contact member 86of the switching unit 85, conductor I 50, contact member H5 of thecontactor II2, conductor I62, contact member 88 of the motor operatedcam 82, energizing winding 164 of the secondary relay or contactor 68,conductors I66 and IE8, contact member I59 of the time delay relay 64,conductor I42, switch 186, conductors I44 and I45, contact member II!)of the controller I00 and conductor I48 to the load conductor 36.

At the same time that the energizing winding IE4 of secondary relay orcontact 68 is energized, the winding 54a, of the secondary conofcontroller I00, and conductor I48 to the load conductor 36.

At the same time that the windings I64 and "Na of the secondarycontactors 58 and 53a are thus energized, a circuit is also establishedextending from the conductor I52 to energize the auxiliary brakingrelays H8 and Him. One of these circuits extends from the conductor me.through the energizing winding I18 of the auxiliary braking relay H3 andconductors I18 and i130 through the switch 45 to the load conductor 3'5,the other circuit extending from the corn ductor I52 through theenergizing winding Flea of the relay IiIla, conductors Him and I lfic,through the switch 48a to the load conductor use. It is thus seen thatthe auxiliary braking relays H8 and IIIc are thus always energized whenthe regulating units are in step and. on position to actuate theircontact members I22 and I221: to circuit opening positions to remove theshunting circuits from the capacitors 8,0 and 8011, respectively, of themotors 32 and 32a, respectively, as will be described more fullyhereinafter. At the same time, contact members I20 and I291; of theauxiliary braking relays H8 and II 8a, respectively, are actuated tocircuit closing positions to connect the energizing windings I82 and IBMof the time delay braking contactors I24 and I24a, respectively. inparallel with the energizing windings of the auxiliary braking relaysIIS and HM whereby the braking contactors I24 and I 24a are so energizedas to actuate their contact members I26 and I'26a to circuit closingposition to connect the terminals I28 and I28a of the motors 32 and 32a,respectively through the switches .44 and 440', respectively, to theload conductors 34 and 34a, respectively, whereby the motors 32 and 32aare conditioned or connected to be energized in response to theregulating systems, as will be described hereinafter.

When the secondary cont-actors and 68a are thus energized, their contactmembers I84-- ills-I88, and I84w--I3Ga -I88a, respectively, are actuatedto circuit closing positions whereby the contact members I and I85aestablish holding circuits for the energizing windings I64 and 34d,respectively, the holding circuit for the contactor 68 extending fromthe energizing winding I64; through the contact member I88,

5 conductor I46, contact member He of controller I59 and conductor I48to the load conductor 35, whereas theholding circuit for the secondarycontactor 68a extends from energizing winding [54a through conductorsidea, [12, contact member I08a of the controller Iflila, conductors I14and IE5, contact member iBS of the ccntactor 68, conductor I46, contactmember H0 of the controller I00 and conductor 48 to the load conductor36. At the same time the contact members I84 and [84a of the secondarycontactors 68 and 88a, respectively, provide a shunt around contactmembers H5 and H511, respectively, of the contactors H2 and I I211,respectively, so that when the contactors H2 and M are energized as tobe described, the energizing circuits "for the secondary contactors E8and 58a are still maintained. Thus the contact member I84 connects theconductor I58 to conductor Hill which is connected to conductor I 62.Likewise the contact member I84a by-passes the contact member lISaconnecting conductor I54 directly to conduct-or I58.

When the contact member 188 of secondary contactor 68 is actuated to itscircuit closing position, it establishes an energizing circuit for themotor controlling relay 12. This circuit extends from conductor 56,through conductor I33, energizing winding I92 of the motor controllingrelay ?2, conductor 94, contact member I88 of the secondary relay 6tand. conductors I96 and I89 through the switch 46 to the load conductor36.

when the motor controlling relay i2 is thus enerits contact members lSBand 293 are actuated to their circuit closing position and contact 2Mand 202 are actuated to circuit interrupting positions. Contact member230 of the relay 12 thus connects the energizing winding 284 o! thecontactor H2 and the energizing winding iii of the braking relay 8! inparallel circuit relation with the energizing winding I 92 oi the relay12 whereby the contactor H2 is energized to actuate its contact membersI I4 and H6 to circuit opening positions and the relay 9'! is energizcdto actuate its contact member 89 to a circuit establishing position.However, since the contact member I84 of the secondary relay 68 is inits circuit closing position, the energizing circuit to the winding I19of the auxiliary braking relay I I8 and to the energizing winding I94 ofthe secondary relay 68 is maintained.

At the same time, the contact member I98 of motor controlling relay I2establishes a motor energizing circuit for the motor 32 which extendsfrom the load conductor 39, through the switch 46, conductors I89 and295, contact member I98, conductors 299 and 298 to a terminal of themotor 32 to connect the capacitor in series with the winding is and fromthe terminal I28 of the motor 32 through the contact member I 29 of thetime delay braking contactor I24 and switch 44 to the load conductor 94.It is to be noted that as the motor 32 is thus energized the main brak-Iing relay 8? functions to establish a circuit extion with the motorenergizing circuit established by contact member I98 of relay I2 andwill therefore not have any immediate effect on the control of theoperation of the motor 32. When thus connected, the motor 32 is operatedin a direction to drive the switch contact members 39 in a direction toeffect an increase in the voltage across the load conductors.

At the same time that the energizing winding I92 of motor control relayI2 is energized, the winding I92a of the motor controlling relay I211 isalso energized to actuate its contact members |98a and 29911 to circuitclosing positions and its contact members 29m and 292a to circuitopening positions. Thus the contact member 299a likewise connects theenergizing winding 294a of the contactor l I2a and the energizingwinding 9 Ia of the main brake relay 87a in parallel circuit relationwith the energizing winding I92a of the motor controlling relay 12a. Thecontact member I98a establishes an energizing circuit for the motor 3211which extends from the load conductor 39a through the switch 46a,conductors IBM and 295a, contact member I981; of the relay 12a,conductors 299a and 298a to a terminal of the motor 320, to connect thecapacitor 89a in series circuit relation with the winding 16a thereofand from I the terminal I 28a through the contact member I261: of thetime delay braking contactor I24a and switch 44a to the load conductor34a. The contact member 89a also establishes an energizing circuitextending from conductor ISIla through contact member 89a of the mainbrake relay 82a, adjustable tap 93a and a portion of resistor 95a,contact member 91a and conductor 299a to the motor 32a, which energizingcircuit is in parallel circuit relation with the energizing circuitestablished by contact member I99a of the relay 12a. The motor 32a isthus energized to drive the switch contact members 39a in a direction tochange the setting of the regulating transformer 29a so as to raise thevoltage across the load conductors.

As soon as-the motors 32 and 92a are thus energized to effect anoperation of the regulating transformers, the motors 92 and 32a drivethe cams 82-84 and 92a-84a, respectively;-whereby the cams 82 and 82aefiect an operation of their.

associated contact members 86 and 99a, respec-- tively, to cooperatewith the contact members 290 and 299a of the motor controller relays 72and 'i2a, respectively, to establish holding circuits for the relays I2and 52a. The holding circuit for the energizing winding I92 of the relayI2 extends from the neutral conductor 59, through conductor I99,energizing winding I92, conductor I94, contact members 299 and 8t,conductor I99 and the switch 49 to the load conductor 39. Such holdingcircuit also provides a holding circuit for the energizing winding 294of the contactor I I2 and the energizing winding 9i of the relay 8?which are connected in parallel circuit relation with the energizingwinding I92 of the motor controller relay 72. Likewise the holdingcircuit for the motor controller relay 12a extends from the neutralconductor 99a, through conductor I99a, energizing winding [92a of therelay 72a, conductor I 94a, contact member 299a of the relay 52a,contact member the controlled by the cam 92a, conductor I990. and switch49a to the load conductor 39a. such holding circuit also provides aholding circuit for the energizing Winding 299:; of the contactor I I 2aand the energizing winding 9 Ia of the relay 81a so as to maintain thecontact member II 4ain a circuit interrupting position and contactmember 89a in a circuit closing position.

Simultaneously with the movement of the cams 92 and 82a, the cams 94 and84a of the switching units 95 and 85a, respectively, are operated todrive the associated Geneva gears 99 and 99a, respectively, to actuatethe cams 92-94 and 9211- 94a, respectively, to efiect a switchingoperation of their associated contact members 96-98 and 95a99c,respectively. As will be noted, the cams 92, 94, 92a and 94a are similarhaving cam portions thereof extending over approximately a fourth of thecircumference of each of the cam members. The cam surfaces of themembers 92 and 94 are displaced 180 and the cams are also displacedabout so that when either one of the cam surfaces of the cam 92 is inposition to effect a circuit closing operation of its associated contactmember 99, the cam portions of the cam member 94 are so positioned thatthe associated contact member 98 thereof is maintained in a circuitopening position. Thus while the cam 92 efiects a circuit closingoperation, the cam 94 effects a circuit opening operation and viceversa. The structure and positioning of the cam members 9211 and 94a isidentical to those'of the cams 92 and 94, so that they operate in'synchronism insofar as the positioning of the cam members effects aswitching operation. Upon completion of a one-step operation of themotor 32 with respect to the regulating transformer 29, the contactmember 96 is operated to a circuit interrupting position and the contactmember 99 is operated to a circuit closing position. Likewise thecontact members 99a and 98a of the switching unit 85a are controlled inresponse to a step operation of the regulating transformer 29a withwhich they are associated.

If both of the motors 32 and. 92a are operated in synchronism so thatthe step operation of the regulating transformers 29 and 29a,respectively, are completed simultaneously, then the contact members 99and 96a. of the switching units and 85a, respectively, are in switchingpositions to establish or maintain the energizing circuit for thewindings I64 and "54a of the secondary relays- 98 and 98a; respectively,if the primary relay 62 is still-energized to demand a further operationof the regulating transformer 20. It will also be understood that uponcompletion of a one-step operation of the regulating transformers 20 and20a that the cams 82 and 82a are operated to open the contact members 86and etc and to actuate the contact members 88 and 88a, respectively, tocircuit closing positions whereby if the contact members so and 93a ofthe switching units 85 and 850: are in their circuit closing positions,then an energizing circuit is established for the secondary relays 68and 88a, respectively. This energizing circuit extends from the neutralconductor 56a of the unit [a, through conductors I52 and lid, contactmember iifia of the contactor H211, conductor I56, contact member 98a ofthe switching unit 85a, conductor 2 l ii, con tact member 98 of theswitching unit 85, conductor I60 and contact member H6 of the contactorH2 to the conductor I52 and from thence through the energizing win-dingsI65 and Rita of the secondary relays 6i and 8811, as describedhereinbefore, to again effect an energization of the motor controllingrelays l2 and 72a to can trol or so energize the motors 32 and 32a toeffect a continuation in the corrective operation of the regulatingtransformers 2c and 20a, respectively.

As stated hereinbefore, upon completion of a one-step operation or" theunits as and 20a, cams 82 and 8211, respectively, are operated toactuate contact members 86 and 86a, respectively, to a circuitinterrupting position. If the relays '53 and 68a are not energized, asdescribed, the movement of the contact members 86 and 88a, respectively,interrupts the holding circuits for relays ii-87 and Ha-81a,respectively, to actuate contact members 198-400 and ISM-209a,respectively, to a circuit interrupting position and contact membersfill-202 and 2llla2ll2a, respectively, to a circuit closing position.However,

contact members 89 and 89a of the main brake relays 81 and 81a,respectively, are not immediately actuated to circuit interruptingpositions since the relays are provided with :a time delay mechanism 99and 99a, respectively.

Contact member 201 then cooperates with contact member 89 of the brakerelay 31 to provide a circuit extending from switch 46 through conductorI80, contact member 89 of relay 31, ad'- justable tap 93, a portion ofresistor 95, contact member 2c: and conductors 238 and 245 to a terminalof the winding of the motor .32, whereby the circuit thus establishedcooperates with the circuit established by the contact member 89 ofrelay 8'! and the contact member 91 of relay [4 to efiectively shunt thecapacitor 80 and connect the windings T6 and '18 of the motor 32 inparallel to produce braking of the motor 32 Such braking circuits aremaintained .for a period of time depending upon the setting oradjustment of the time delay mechanism 99 associated with the main brakerelay 81.

Likewise, contact member vZl'l la cooperates with contact member 89a ofthe brake relay 81a to establish a circuit extending from switch 46athrough conductor 180a, contact member 89a of relay 81a, adiustable tap93a and a portion of resistor 35a, contact member m of relay 1.211 andconductors 238a and 240a to a terminal of the winding 16a of the motor32a. Likewise, the circuit thus established cooperates with the circuitestablished by contact member 89a of relay 81a and the contact member91a of relay Ma to effectively shunt the capacitor 800. and connect thewindings l-Ba and 78a of the motor 32a in parallel to effectivelybrakethe motor (1.. Nonmal braking of the motors 32 and 32a is thusaccomplished by the cooperation of the main braking relays 87 and 87awith the relays l2 and 52a, respectively.

if, however, the brake relay 3? or the relay should fail to operateproperly, the motor 32 would tend to continue to operate after thecompletion of the regulated step operation with the result that thetransformers 2c and its would be operated out of step. Likewise, ifduring the regulating operation one of the transformers, for example 20,was to be operated at a faster rate oi change than the rate of change ofthe step operation of transformer 20a, the transformers would tend to beoperated out of step. Such results are, however, impossibie in thissystem where the switching units 35 and s. are utilized with the interconnections therebetween and the controi of the auxiliary brake relaysH8 and iita which constitute emergency brakes for the motors in case offailure of the main braking system described.

Thus, if motor 32 tends to operate beyond the regulated step operationrequired or if it operates at a faster rate than motor 32c, the contactmember E6 of the switching unit 35 will be operated to its circuitinterrupting position before the operation of the contact member We ofthe switching unit 85a and the contact member so or the switch unit 85will be actuated to a circuit closing position while the contact member93a of the switching unit 85a is still in a circuit interruptingposition. This will effectively interrupt the energizing circuits of thewindings iiS l and i84a, or" the secondary relays -68 and 58a,respectively, even though the primary relay 52 continues to call for aregulating operation in the raise direction. Thus, until the regulatingoperation of the regulating transformer 29a is completed the energizingcircuits to the windings iS l and l64a of the secondary relays 6t and68a will be interrupted until completion of the step operation of theregulating transformer 20a and the actuation of the contact member 9%toa circult interrupting position and of contact member 98a to a circuitclosing position is effected. It is thus seen that the switching units85 and 85a cooperate generally when one of the units is a master unitand the other a follower unit to maintain the regulating operations instep.

It is also to be noted that instead of depending only upon the stepoperation of the switching units 85 and 85a, a more positive method ofmaintaining the units in step is provided by the use of the contactmembers 8-8 and 88a of cams 82 and 82a, respectively. Thus, the contactmembers 88 and 88a are actuated to circuit inter-rupting positions assoon as the regulating operation is initiated, thereby interrupting theenergizing circuit for the relay windings E64 and ifila, respectively.As the relays 68 and 6-80. are thus selectively deenergized, contactmembers i84- I85 and ISM-486a, respectively, are actuated to 'circuitinterrupting positions, and if one of the regulating units operates at afaster rate than the other, the faster unit will be "forced to stop uponcompletion of a step operation until the slower unit completes itscorresponding step operation, at which point the switching units 85 and85a will again be in step to initiate the energizing circuits for therelays 68 and 88a if the primary relay 52 still calls for a regulatingoperation in the raise direction.

Specifically, as the motor 3-2 is energized to effect a regulatingoperation of the transformer- 2d, the energizing circuit to the windingI64 oi the secondary relay 53 is interrupted by movement of the contactmember 88 to a circuit opening position. This normally efiectsdeenergization of the secondary relay 68 to actuate its contact membersI86 and WA to circuit interrupting positions, and since the contactor H2is still energized by reason of the contact member 86 being in'circuitclosing position, the energizing circuits to the auxiliary brakingrelays H8 and HM are interrupted, the contact members I22 and I22a,respectively, are actuated to their circuit closing positions andcontact members I26 and I2ila, respectively, are actuated to theircircuit interrupting positions. Contact members I22 and H211, however,are not, as yet, effective for establishing the auxiliary or emergencybraking circuit, as will be described hereinafter, whereas contacts H28and Mia interrupt the energizing circuit of the windings iBZ and 582a,respectively, of the time delay braking contactors I2 1 and 24m However,the contactors I24 and I2da are provided with predetermined time delaycharacteristics and contact members I26 and I26a are maintained incircuit closing position for a predetermined time after the contactorsI24 and Wm are deenergized. Thus, the contact members i26 and i26amaintain the energizing circuits for the motors 32 and 32a until suchenergizing circuits are interrupted by an operation of the motorcontrolling relays I2 and ":2a, respectively.

As described hereinbefore, upon completion of the one-step operation ofthe motors 32 and 32a, the cams 82 and 82a, respectively, actuate thecontactmembers 86 and 86a, respectively, to interrupt the holdingcircuits for the motor con trolling relays I2 and 7241, respectively,thus at the same time interrupting the energizing circuits for thewindings 2M and Edda, respectiveiy, of the contactors i I2 and II2a,respectively, with the result that the contact members I I4 and 3 Idaare returned to their circuit closing positions. Thus, if the switchingdevices 85 and 850. are out of step so as to interrupt the energizingcircuit for auxiliary braking relays H8 and Iida, the contact member Iidcooperates with the contact member I22 of the deenergized relay lit toefiectively shunt the capacitor 80 of the motor 32 and connect thewindings i5 and 78 thereof in parallel circuit relation to effectivelybrake the motor 32 even if the main brake relay 8'! fails to functionproperly. Likewise, upon completion of a onestep operation of the motor32a, if the motors and consequently the devices 85 and 35a are out ofstep, the contact member i Ma cooperates with the contact member I221;to effectively shunt the capacitor 80a of the motor 32a and connect thewindings 16a and Eta in parallel circuit relation to effectively brakethe motor 320. if the main brake relay 81a fails to function properly.

The braking action obtained by shunting the capacitor and connecting thewindings of the the rotor current can be regarded as havingtwocomponents, namely a field component in the axis of the main fieldand a cross field component substantially in time and space quadraturewith the main field component. The motor torque is developed by thereaction of the main field component of the rotor current with the fluxset up bythe cross field component while a negafive qr en r t torque i elq r ac ion.

12 of thecross-field current with the main field flux. Now if the motorhas two identical windings, as described hereinbefore, 90 electricaldegrees apart, as in the reversible capacitor motor described, and thesewindings are connected in parallel across a single-phase line while themotor is running, the resultant main field of the two windings will beequivalent to that of a single winding halfway between them. Thi fieldwill result in a cross-field current in the rotor which sets up across-field fiux in a direction at right angles to the field of thesingle equivalent winding. This cross-field flux induces a circulatingcurrent in the two parallel connected conductor windings. Thiscirculating current flows in a circuit of low impedance which has closemagnetic linkage with the cross field and the cross field flux is dampedto almost zero. Since the motor torque is produced by reaction of thisflux with the main field component of the rotor current, the motortorque is reduced to a very small value. The cross-field component ofthe rotor current is substantially increased, since its field isvirtually damped out. Since the main field iiuX with which this currentreacts is not substantially afiected, negative or braking torque will beconsiderably increased. The resultant torquewith proper value of rotorresistance will be'a strong braking action. Since the cross-fieldcurrent decreases with the speed and becomes zero at standstill, thebraking action also decreases to zero and the motor comes to a stop withno tendency to reverse.

If the load I2 should vary so as to require a regulating operationof thetransformer to de-.

crease the voltage across the load conductors, then the primary relay 52is so energized as to actuate its contact member 58 into engagement withthe contact member 52 to efiectively ener-- gize the energizing winding2 l 2 of the time delay relay 66. This energizing circuit extends fromthe neutral conductor 56, through contact member I32 of the controllerI00, conductor I38, contact members 58 and 62 of the primary relay 52,energizing winding 2I2 of the time delay relay 66, conductor I42, switchI36, conductors I44 and I46, contact member III) of the controller Hillthe contactor IIZa, conductor I56, contact mem ber 96a of the switchingunit 85a, conductor I58, contact member 96 of the switching unit 85,conductor I59, contact member H6 of the contactor H2, conductor I62,cam-operated contact mem-. ber 88, energizing winding 2I8 of the relayi0,

' conductors ZIs and 223, contact member 2 of the time delay relay 65,conductor I42, switch I36, conductors His and I46, contact member IIB.

of 'the controller I88 and conductor I48 to the load conductor 36. Atthe same time the energizing circuit is established for the winding 2I6ai3 224, 218 and contact member IN or the time delay relay 56, conductorHi2, switch 1-38, con ductors M4 and I46, contact member H!) of con:troller all and conductor M8 to the load condu'ctor 33.

v As will be evident, energizing windings H6 and N65; or the auxiliar oremergency braking relays H8 and H811, respectively, will also beenergized in the same manner as described with reference to the raiseoperation previously dcscribed herein.

When the secondary relay in is thus energized, it operates to actuateits contact members 226-, 228 and 236 to circuit closing positions sothat its contact member 228 will establish a holding circuit for therelay l and the contact member 225 will effectively shunt the contactmember 1 it of contactor l 12. The holding circuit established bycontact member 28 may be traced from the conductor 62, through thecontact member 88, energizing winding 2 of the relay it, contact member228 conductor contact member I'l'fl of controller its and conductor I58to the load conductor Lil-:ewise, the circuit for the en'- ergizingwinding iii-a may be traced from the conductor I62, through the contactmember 88a, energizing Winding flea, conductors 218a and 222, contactmember was of controller 103a, condu'ctors 22d and 2228, contact member228 of the relay ill, conductor 145, contact member lid of thecontroller [t8 and conductor Hi3 to the load conductor 35.

When the secondary relay or contactor ii! is lishes an energizingcircuit for the motor oon troller relay it, which extends from theneutral conductor 53, through conductor I86, energizing winding 232 ofthe relay M, conductor 3:2, contact member 238 of the secondary relayill, conductors E95 and E89, and the switch to the load conductor 33. Atthe same time, the contact member 202 of the deenergized motor controlrelay 12 is effective for connecting the energizing winding 2% of thecontactor H2 and the energizing winding 9! of the main brake relay 8'.in parallel circuit relation with the energizing winding of motorcontroller relay we so as to effect an operation of the contact membersH4 and H5 of thecontactor l 12 to circuit opening positions and thecontact member 89 of relay 8? to a circuit closing position. Since thecontact member 2253 of the secondary relay it) is in the circuit closingposition, the energizing circuit for the auxiliary braking relay H8 andfor the secondary relay 0 is maintained even though contaetor I 12 isenergized. When the motor controller relay I4 is thus energized, itscontact member 235 establishes a motor energizing circuit which extendsfrom the conductor through the switch 48, conductors lafl a'nd 2135,contact member 236, conductors 238 and 241) to a terminal of the motor32 to effectively connect the capacitor 80 thereof in series with thewinding Z8 so as to sheet an operation of the motor in a direction todrive the switch contact members 30 to effect an operation of theregulating transformer 20 to decrease the voltage across the loadconductors.

Since the main brake relay 8'! is energized "at the same time as therelay in, a circuit is established extending from the switch throughconductor I80, contact member 89 of the brake relay 81, adjustable tap93, a portion of the resistor 95, contact member Zlll of thede'energized relay l2, and conductors 238 and 240 to a terminal of themotor winding 16. Thiscircuitis in riarallel 14 with the circuitestablished by contact member 236 of relay 14 and, therefore, has noimmediate efict on the control of the operation of the motor 32.

At the same time the secondary relay 10a is effective for establishingan energizing circuit for the motor control relay no, this circuitextending from the neutral conductor 56a through conducto'r 19M,energizing winding 232c of the relay ldc, conductor 234d, contact member23011 or the secondary relay 10a, conductors 196a and [8021 through theswitch 48a to the loadconducter 3611, At the same time the contactmember 202s of the motor cont1-olrelay 12a is effective for connectingthe energizing winding 204d of the con-'- tactor H20, and the energizingwinding 91a oi the brake relay "81a in parallel relation with theenergizing winding 2 32a of the relay Me. 'When the motor control relaylid is thus energized, its contact member 736a establishes a motorencrgizi-ng circuit for the motor 320. which extends from conductor Etathrough the switch 46a, conductor [890a, conductor 295a, contact member235a, conductors 233a and 2 38a to a terminal of the motor 32a toconnect the capacitor a in series with the winding 18c and to so eiieotthe energization of the motor 32a as to effect an opera ation thereof ina direction to drive the switch contact members 30a in a direction toeffectively change theconnections'of the transformer 20a'to decrease theVoltage across the load conductors. The circuit established by contactmember 89a of brake relay Bio and the contact member 20H; of deenergizedrelay 12a is in parallel with the energizing circuit established bycontact member 2360: of relay Ma and will therefore have no immediateeffect on the control of the motor 32a.

When themotors 32 and 32a are thus energized to effect an operationthereof, the cams {Sband 82a--'84'a, respectively, are driven asdescribed he'reinbefore. Movement of the cam '82 again permits movementof the contact member 88 to open circuit position to "interrupt theenergizing circuit forthe secondary relay "Land also effects themovement or the contact member 85 to a circuit closing position'so as toestablish a holding'circuit for the motor control relay T4. This holdingcircuit extends from conduct-or "58 through conductor tilt, energizingwinding "23-2 of the relay l4, conductors 234 and 2 12, contact member202 of the deenergized motor'controlrelay 12, contact member 86 andconductor *lBll through the switch 46 to the load conductor 3 3. Holdingcircuits for the energizing windings 91 and 204 of the relay'il'i andcontactor I I Z'ar'e also maintained by the contact member 88. Thewinding 232 of the'motorcontrol relay [4 isthus energized while themotor 32 operates through a one-step operation of the regulator anduntil the cam 82 is rotated to the position shown to actuate the contactmember 85 to an open circuit position. Likewise movement of the cam 82aof the unit l-lla actuates the-contactmember 88a to an open circuitposition'to interrupt'the energizing circuit for the'winding 2 l to ofthe secondary relay 10a and the contact member 86a is actuated to acircuit closing position to establish a holding circuit for the motorcontrol relay 14a, the brake relay 8l'a and contactor "H'Za. Thisholding circuit extends from the neutral conductor 56a through conductorlcca, energiz'ing winding 232a, conductors 234a and "2 42a, contactrn'ember 282a of thedeenergized relay 1 2d, contact member 86a of thecam operated the movement of contact members 85 and 86a,

respectively, interrupts the holding circuits for relays l4-8l andMa-81a, respectively, to actuate contact members 236 and 236a,respectively, to a circuit interrupting position and contact members 91and 91a, respectively, to a circuit closing position. Because the timedelay mechanism 99 and Eta, maintains the contact members89 and 89a,respectively, in circuit closing position for a predetermined period oftime after the energizing windings SI and 91a of brake relays 87 andtie, respectively, are deenergized, contact member 89 cooperates withcontact member 97 of relay l to provide an energizing circuit to theterminal of winding '58 of the motor 32. This latter energizing circuitcooperates with the energizing circuit established by contact member 89and contact member 25! of deenergized relay 72 to efiectively shunt thecapacitor 80 and connect the windings l6 and E3 of motor 32 in parallelcircuit relation to efiectively brake the motor. A similar braking ofmotor 32a is also obtained by a similar operation of the main brakerelay 81a.

During the normal operation of units 20 and 20a, the switching units 85and 850., respectively are driven in a manner similar to that describedhereinbefore to control the positioning of the contact members 9698 andSta-98a, respectively, so as to control the energizing circuit to thesecondary relays Hi and 10a to maintain them energized when the primaryrelay 52 is energized only so long as the switching units 85 and 85a aredriven in synchronism by the motors 32 and 32a, respectively. As in theprevious example when the secondary relay it or 10a becomes deenergized,the contact members 226 and 228a, respectively, thereof are actuated toa circuit interrupting position, and since the contactors H2 and H211,respectively, are energized to their open circuit position, theenergizing circuits to the auxiliary or emergency braking relays H8 and8a, respectively, are interrupted so that the contact members I22 and122a are returned to their circuit closing positions. However, as longas the motors 32 and 32a are operating in response to the energizationof the motor control relays i4 and 14a, respectively, the contactors H2and HM, respectively, are energized to maintain their contact members H4and Him, respectively, in an open circuit position. Upon completion of astep operation of the regulating transformers 29 and 20a, the cams 82and 82a are rotated to again actuate the contact members 86 and 860.,respectively, to open circuit positions whereby the energizing windings204 and 204a of contactors H2 and 2a, respectively, are deenergized andthe contact members H4 and Hta, respectively, are actuated to theircircuit closing positions. If the regulators and consequently theswitching devices 85 and 8511 are out of step so that auxiliary brakingrelays H8 and IlBa are deenergized, then the contact members H 3 and IMacooperate with the associated contact members 122 and [22a,respectively, of the auxiliary braking relays H8 and 8a to efiectivelyshunt the capacitors 80 and 80a and connect the windings of motors 32and 16 32a, respectively, in parallel to effectively and immediatelybrake the motors even though the main braking relays 81 and 81a fail toproperly function.

If it is desired to have the unit Ilia as the master unit instead ofunit I0, then the controller lilta is moved to the master or No. 3position where contact members IHla and "32a engage their correspondingfixed contact members and the controller Hill is moved to the followeror No. 1 position where contact members I04 and IE8 engage theircooperating fixed contact members. With such a positioning of thecontrollers Iii!) and Hilla, it is seen that since the contact member182 of the controller I00 is in the open circuit position, it isimpossible for the time delay relays E4 and E6 to be energized.

Assuming that the switch 136a. is in its circuit closing position, ifthe load l2 should change so as to cause a decrease in the voltageacross the load conductors, then the primary relay 52a of unit 10a isenergized so as to efiect an engagement of the movable contact member5811 with the fixed contact member tea. Under such circumstances, acircuit is established which extends from the neutral conductor 55a,contact member I621: of the controller Illila, conductor l38a, contactmembers 58a and 60a of the relay 52a, energizing winding Ifla of thetime delay relay 64a, conductor l42a, switch 136a, conductors Mia andNita, contact member Ilfla of the controller ltea and conductor 148a tothe load conductor 35a. This effectively energizes the time delay relay54a. providing the energization of the primary relay 52a is ofsufiicient duration, whereby the contact member i5ila of relay B ia isactuated to a circuit closing position to cooperate with the switchingunits and 85a to establish an energizing circuit for the secondary relay68a.

The energizing circuit for the relay 6811 thus established extends fromthe conductor 56 through conductors 152 and S54, contact member H6a ofthe contactor 2a, conductor I56, contact member a of th switching unit8511, conductor 553, contact member 96 of the switching unit 85,conductor 16B, contact member H6 of contactor H2 to the conductor H2 andfrom thence through contact member 88a of th cam operated contacts,energizing winding 34a of the secondary relay 68a, conductors lfita and[68a, contact member 159a of the time delay relay 64a, switch itia,conductors MM and Idea, contact member llta of the controller Nita andconductor |48a to the load conductor 35a. At the same time the auxiliarybraking relays H8 and 8a are energized, as described hereinbefore, withthe result that time delay braking contactors H4 and i250; are alsoenergized. Likewise a circuit is completed from the conductor I52through the cam operated contact member 88, energizing winding we ofsecondary relay E8, conductors I65 and I'M, contact member I08 ofcontroller Hlil, conductors H2, 585a and ISBa, contact member a of thetime delay relay 64a, switch 136a, conductors [Ma and M611, contactmember llfla of the controller iota and conductor 88a to the loadconductor 35a whereby the secondary relay 68 is energized simultaneouslywith the energization of the secondary relay 680..

When the secondary relay 68a is thus energized, its contact members 184aand iflfia are actuated to a circuit closing position whereby contactmember l84a shunts the contact member Ba and the contact member I86aestablishes a holding circuit for the relay 68a which extends from theenergizing Winding Ifia through the contact member I86a, conductor I45a,contact member IIOa of controller I081; and conductor 8a to the loadconductor 35a. Since the energization of the secondary relay E53 in thisoperation is dependent upon the energization of the secondary relay 68a,both of the secondary relays are maintained energized so long as theholding circuit for the relay 68a is maintained.

With the relays 68 and 63a energized, as described, th operation of themotor controlling relays I2 and 12a, respectively, and the resultantoperation of the motors 32 and 32s are as described, hereinbefore whenthe unit I was the master unit. It is quite evident that as soon as theswitching units 85 and 85a are operated to be out of step either byreason of failure of the main brake relays 2'! and 87a, respectively, orbecause on unit is driven faster than the other, that it is impossibleto energize the secondary relay 68a with-the result that a further stepoperation' of the motors 32 and 320: will be impossible until theswitching units 85 and 8511 are brought into step relation, therebyinsuring simultaneous operation of the regulating transformers 20 and20a to maintain them in step.

If the change in the load condition should be such as to effect anincrease in the voltage across the load conductors, then the primaryrelay 52a is energized to actuate its movable contact member 58a intoengagement with the fixed contact member 62a to establish an energizingcircuit for the time delay relay 66a. This circuit extends from theneutral conductor 56a through contact member I02a of controller Iota,conductor I 38a, movable contact member 58a of the relay 52a, fixedcontact member 52a, energizing winding 2I2a of the time delay relay 66a,conductor I42a, switch I36a, conductors MM and MM, contact member IIUaof the controller IBM and conductor H811 to the load conductor 36a. Thusif the energization of primary relay 52a is of suificient duration toovercome the time delay characteristics of the relay 66a, the relay 66ais energized to actuate its contact member 2I4a to a circuit closingposition to eifect the energization of the secondary relays a and I0.

With the contact member 2I4a in circuit closing position, a circuit isestablished which extends from neutral conductor 56 through conductorsI52 and I54, contact member ilta of the contactor II 2a, conductor I 56,contact member 95a of the switching unit 851:, conductor I58, contactmember 96 of the switching unit 85, conductor I60, contact member I isof the contactor IIZ, conductor I62, contact member 88a, energizingwinding 2I6a of the secondary relay lea, conductors 2I8a and 229a,contact member 2I4a, switch I36a, conductor I 44a and MM, contact memberI Illa of controller Illfla and conductor 8a to the load conductor 36a.

At the same time an energizing circuit is established for the secondaryrelay I0 which extends from the conductor I62 through the contact member88 of the cam operated contacts, energizing winding 2I6 of the relay1!], conductors 2I8 and 224, contact member I04 of the controller I00,conductors 222, 2I8a and 22011, contact member 2I4a of the time delayrelay 66a. conductor-2a, switch I36a, conductors I 44a and I 46a,contact member IIOa of the controller I001; and conductor H811 to theload conductor 38a; simultaneously with the energization of he isecoeryrelaysio and we the auxiliary l8 braking relays I I8 and I I8a arealso energized as described hereinbefore.

When the relay 10a is thus energized, its contact member 226aeifectively shunts the contact member I Ilia and contact member 228a isactuated to establish a holding circuit for the relay 10a. This holdingcircuit extends from the energizing winding 2I6a through the contactmember 228a of relay Illa, conductor MBa, contact member I Illa of thecontroller IilOa and conductor H811 to the load conductor 36a. At thesame time the contact member 230a of the motor control relay 10a isactuated to a circuit closing position to effect an operation of themotor control relay Ma to establish the energizing circuits describedhereinbefore for the motor 32a to effect an operation thereof to drivethe switch contact members 30a in a direction to cause the regulatingtransformer to increase the voltage across the load conductors.Simultaneously, the secondary relay 16 of unit II) is effective so thatthe contact member 230 thereof establishes the energizing circuit forthe motor control relay I4, whereby the relay I4 is e'fiective forestablishing the energizing circuit for the motor 32 to eifect anoperation thereof to drive the switch contact members 30 in a directionto change the setting of the transformer 29 and eifect an increase inthe voltage across the load conductors.

As in the previous cases, if the switching units and 85a are not drivenin synchronism or if the main braking relays 81 and 81a fail, theenergizing circuits for the secondary relays of the units I 8 and Illaare interrupted whereby neither of the units can be operated until bothunits have completed a step operation. Likewise when the step operationhas been completed and the cams 82 and 82a are effective for actuatingtheir contact members 85 and 85a to a circuit interrupting position, thecontactors H2 and II2a, respectively, are deenergized whereby theircontact members H4 and H441, respectively, cooperate with the contactmembers I22 and I22a, respectively of the auxiliary braking relays whenthe switching devices 85 and 85a are out of step for effectivelyshunting the capacitors 89 and 89a and connecting the windings of themotors 32 and 32a in parallel circuit relation to effectively brake themotors.

If for some reason it is desired to have the units In and Illa operateas independent units, then the master controllers I 08 and IBM are movedto their independent or No. 2 positions where the contact membersI02-I06I I0 and I 02a,I08a--I I (Ia, respectively, engage theircooperating fixed contact members. Under such circumstances, the contactmembers I82 and "12a engage their cooperating fixed contact memberswhereby the movable contact members 58 and 58a of the primary relays 52and. 52a, respectively, are connected through the contact members I02and IBM, respectively, to their respective neutral conductors 56 and56a, so that when either, or both, of the primary relays 52 or 52a areenergized, they will be effective for establishing energizing circuitsfor their associated time delay relays 64-435 and 64a66a, respectively,depending upon the direction of movement of the associated movablecontact members.

At the same time, it is to be noted that contact members I06 and Iota ofthe controllers I09 and ifiIla, respectively, cooperate to shunt theswitching units 85 and 85a from the energizing circuits for thesecondary relays 68- -11 and 68a 1i1a. This is evident from the circuitestablished which extends from the neutral conductor Eta of unit Illathrough conductors I52 and Etta, contact member 59541 of controllerItila, conductor contact member IElG of controller Hit and conductor 18%to'the conductor I62. Thus when the controllers IE9 and IiiBa are intheir independent or No. 2 positions to establish the circuit to theconductor I62, if the primary relay 52 is energized. so as to effect theengagement of'contacts 58 and 68 to establish the energizing circuit forthe time delay relay circuit then the energizing winding Ifid of thesecondary relay 631s energized by a circuit which extends from theconductor I52 throughthe cam operated'contact member 83, energizingwinding i% l,conductors I56 and see, contact member I59 of the timedelay relay conductor M2, switch I36, conductors Md and I l-6 throughthe contact member Iii? of controller I60 and the conductor its to theload conductor 36. Similarly, if the primary relay 52 is energized tooperate its movable contact member 58 to engage the fixed contact member62 so as to effect an energization of the winding 2I2 to operate thecontactmember 2M of the time delay relay to to a CllCL it closingposition, anenergizing circuit is established for the secondary relay itwhich extends from the conductor see through the cam operated contactmember 83, energizing windings 2m, conductors 2I8 and 22B, contactmember 22 3 of the time delay relay 66, conductor Hi2, switch conductorsI44 and Mt, contact member iii? of the controller Iili! and theconductorH 58 to t -e load conductor 35. It is thus seen that the control of themotor-control relays l2 and i can be efiected by controlling theenergization of the secondary relays 68 and ii] in the same manner asdescribed with reference to the master-follower connections describedhereinbefore.

Similar connections are established for independent operation of theunit IOa'but for purpose of simplification will not be described, itbeing understood that once the controllers I55; and IIlila are in theindependent or No. 2 position described so as to shunt the switchingunits 85 and 85a, that the operation of the units I and Ilia/will beidentical to that described with reference to the unit It].

If during the operation of the units it becomes desirable to operateeither of the'units manually r for example unit 58, so as to bring theregulating transformers 2i! and Eta into step, then such manualoperation or" the regulating transformer 20 may be effected by placingthe controllers I09 and Iiida in the independent or No. 2position-described hereinbefore and actuating the switch I33 to the opencircuit position illustrated so as to remove the automatic control fromthe regulating system and the auxiliary control switch 135 may beoperated so as to selectively move its contact members i32 or 13!; intoengagement with the cooperating fixed contact members depending uponwhether it is desired to effect a raising or a lowering of the voltageon the load conductors. Thus, for example, if the auxiliary controlswitch tell is actuated to a position where its contact member it? is inengagement with its fixed cooperating contact members, an energizingcircuit for the secondary relay t8 is established which extends from theconductor 55c through conductors I52 and 254a, contactmember Idea of thecontroller iiiila, conductor 246, contact member I of controller Hit,conductors I89 and I52, cam operated contact member 88, energizingwinding I64 of the relay t8, conductors I 66 and IE8, contact member I32of the auxiliary controlswitch 13c, conductors M4 and I46, contactmember III) of the controller IM and conductor I48 to the load conductor36. Similarly, an energizing circuit for the secondary relay "ii! may beestablished by actuating the auxiliary control switch I36 to a positionwhere its contact member ISA engages the cooperating fixed contactmembersto establish a similar circuit which extends from the conductorI62 through the cam operated contact member 88, energizing winding 2 Itof the relay 10,'conductors 2 I3 and 220, contact member I35 of theauxiliary control switch, conductors Hi l and I'fi, contact member Hitof the controller I06 and conductor use to load conductor 36. Theoperationof the motorcontrolling relays I2 and 14 in response to anenergization of the secondary relays '68 and 'iii is identical to thatdescribed hereinbe'fore with reference to the automatic operationof thesystems.

In all cases of automatic operation wherebne of the units is a masterand the other as follower, it is apparent that the auxiliary oremergency braking relays H8 and 8a are simultaneously energized and thatif the units and consequently the switching devices 35 and a are out ofstep, the contactors H2 and 2:2, respectively cooperate with theemergency braking relays H8 and Ilsa, respectively, to effectsubstantially instantaneous braking of the associated motors 32 and 32awithout any overrun of the motors even though the main braking relays8'! and 81a fail to function properly. The positive braking of each ofthe motors by the auxiliary braking relays IIB and H80. upon completionof a step operation thus eiiectively cooperates with the switching units85 and B'Ea'to aid in maintaining the regulating transformers 2i! and29a, respectively, in step so that there will beno unbalance of the loadon the transformers. The time delayprovided for the contactors I24 andI241: is sufficient to insure that their contact members I26 and a aremaintained in circuit closing position a sufiicient period of time afterthe contactors I26, and I24a, respectively, are deenergized so as tomaintain the associated motors "32 and 32a, respectively, connected sothat efie'ctive braking power can be applied to the motors uponcompletion of a one-step operation of the regulating transformers.

In conclusion, it is pointed out that while the illustrated examplesconstitutepractical embodiments of my invention l do not limit myself tothe exact details shown, since the modifications of the same may beconsiderably varied without departing from the spirit of the inventionas defined in the appended claims.

I claim as my invention:

1. In a motor control system 'for'a mastermotor and a slave motor, incombinatioma plurality of motors, each of the motors beingof'the'spli'tphase capacitor type having two substantially identicalsingle-phase windings and a phaseshifting capacitor disposed to beselectively connected in series with one or the other of the windings tocontrol the directional rotation of the associated motor, a pair ofcontactors for each of the motors disposed to be selectively energizedto control the'series connection of the capacitor with'the windings ofthe respective motor,a control means for each pair of contactors forinitiating the control of the operation of its respective motor in onedirection or the other, intercon nect'ed switching means'forrenderingoneof the motors a-master andone of the-motors a -followerand for renderingonly the control means of the master motor'operative to control theselective energization of each of the pairs of contactorsassociated withthe master motor and the slave motor,-respectively, the switching meansincluding a step switch for each of the motors disposed for operation toestablish the interconnections only upon completion of a step operationof the motors where the motors are in step, contact means associatedwith each of the motors disposed to be simultaneously energized when theinterconnections are established by the switching means'to connect eachof the motors to beofmotors, each of the-motors being of the splitphasecapacitor type having two substantially identical single-phase windingsand a phaseshifting capacitor disposed to be selectively connected inseries with one or the other of the windings to control" the directionalrotation of the associated motor, a pair of contactors for each of themotors disposed to be selectivelyenergized to control the seriesconnection of the capacitor with the windings of the respective motor, acontrol means for each pair of contactors for initiating the control ofthe operation of its respective motor in one direction or the other,interconnected switching means for. rendering one of the motors a masterand one of the motors a follower and for rendering only the controlmeans of the master motor operative to control the selectiveenergization of each of the pairs of contactors associated with themaster motor and the slave motor, respectively, the switching meansincluding a step switch for each of the motors disposed for operation toestablish the interconnections only upon completion of a step operationof the motors where the motors are in step, contact means associatedwith each of the motors disposed to be simultaneously energized when theinterconnections are established by the switching means to connect eachof the motors to be directionally energized in accordance with theselective energization of the pair of contactors associated therewith,another contactor associated with each of the motors disposed tofunction when the associated pair of contactors and said contact meansare deenergized to cooperate with said contact means to shunt thephase-shifting capacitor and connect the single-phase windings of theassociated motor in parallel circuit relation to effectively brake themotor, and time delay means associated with each of said contact meansto maintain the connection of the associated motor for a period of timeafter said contact means is deenergized to insure the effective brakingof the motor.

3. In a motor control system for a master motor and a slave motor, incombination, a plurality of motors, each of the motors being of thesplitphase capacitor type having two substantially identicalsingle-phase windings and a phaseshifting capacitor disposed to beselectively con- 22 nectedin series wlth one or the other of thewindings to control the directional rotation of the associated motor, apair of contactors for each of themotors disposed to be selectivelyenergized to control the series connection of the capacitor with thewindings of the respective motor; a'control means for each pair ofcontactors for initiating-the control of the operation of itsrespective-motor in one direction or the other and disposed foroperation to selectively energize the contactors, switching meansassociated with each of the control means disposed to be'actuated by themotor associated therewith, a switching device associated with each ofthe control means disposed for selective manual operation to establishinterconnections between the control means and motor operated switchingmeans'associated with the motors to establish one of the motors as amaster and one of the motors as a follower, the manually operatedswitching devices and the motor operated switching means therebycooperating to eifect a simultaneous selective energization of thecontactors when the control means of the master motor is energizedto'selectively control theconnections of the master and slave motors tocomplete a step operation of the master and slave motors. the motoroperated switching means being disposed to interrupt the energization ofthe control means when the master and slave motors are out of step,contact means associated with the master and'slave motors disposed to besimultaneously energized, when one of the motors is the master and oneof the motors is a follower and said' "interconnections are established,to connect the master and slave motors to be selectively energized inaccordance with the selective energization of the pair of contactarsassociated therewith, and another contactor associatedwith' each of themaster and slave motors disposed t'ofunction when the associated pair ofcontactors are deenergized to cooperate with said contact means to shuntthe phase-shifting capacitor and connect the single phase windings ofthe associated motor in parallel circuit relation to effectively brakethe motor.

4. In a motor control system for a master motor and a slave motor, incombination, a plurality of motors, each of the motors being of thesplit-phase capacitor type having two substantially identicalsingle-phase windings and a phase-shifting capacitor disposed to beselectively connected in series with one or the other of the windings tocontrol the directional rotation of the associated motor, a pair ofcontactors for each of the motors disposed to be selectively energizedto control the series connection of the capacitor with the windings ofthe motor, another pair of contactors associated with each motordisposed to be selectively energized to control the selectiveenergization of said motor control contactors, a control means for eachanother .pair of contactors for controlling the initial selectiveenergizaton of said another pair of contactors under predeterminedoperating conditions, a switching means associated with each of saidanother pair of contactors disposed to be actuated by the motorassociated therewith, a manually operated switching device alsoassociated wtih each of the motor operated switching means disposed forselective operation to cooperate with the motor operated switching meansand said another pair of contactors associated with the motors toestablish interconnections therebetween to establish one of the motorsas a master and one of the motors as a follower, I

the follower motor ineffective and connecting said another pair ofcontactors to be selectively energized by the control means of themaster motor when the motor operated switching means are in step with o.e another, contact means associated with each of the motors disposed tobe simultaneously energized with the initial energization of saidanother pair of contactors to connect each of the motors to bedirectionally energized in accordance with the selective energization ofthe pair of contactors associated therewith, and another contactorassociated with each of the motors disposed to function when theassociated pair or" contactors and said contact means are deenergized tocooperate with said contact means to shunt the phase-shifting capacitorand connect the single-phase windings of the associated motor inparallel circuit relation to effectively brake the motor.

5. In a motor'control system for a master motor a slave motor, incombination, a plurality of motors, each of the motors being of thesplit-phase capacitor type having two substantially identicalsingle-phase windings and a phase-shiiting capacitor disposed to beselectively connected in seri s with one or the other of the windings tocontrolthe directional rotation of the associated motor, a pair ofcontactors for each ofthe motors disposed to be selectively energized tocontrol the series connection of the capacitor with the windings of themotor, another pair of contactors associated with each motor disposed tobe selectively energized to control the selective energization of saidmotor control contactors, a control means for each said another pair ofcontactors for controlling the initial selective energization of saidanother p'air of contactors under predetermined operating conditions, aswitching means associated with each of said another pair of contactorsdisposed to be actuated by the motor associated therewith, a manuallyoperated switching device also associated with each of the motoroperated switching means disposed for selective operation to cooperatewith the motor operated switching means and said another pair ofcontactors associated with the motors to establish interconnectionstherebetween to establish one of the motors as a master and one of themotors as a follower,

the manually operated switching device of the follower motor renderingthe control means of the follower motor ineffective and connecting saidanother pair of contactors to be selectively energized by the controlmeans of the master motor when the motor operated switching means are instep with one another, contact means associated with each of the motorsdisposed to be simultaneously energized with the initial energization ofsaid another pair of contactors to connect each of the motors to bedirectionally energized in accordance with the selective energization ofthe pair of contactors associated therewith, another contactorassociated with each of the motorsdisposed to function when theassociated'pairof contactors and said contact means are deenergized tocooperate with said contact means to shunt the phase-shifting capacitorand connect the single-phase windings of the associated motor inparallel circuit relation to effectively brake the motor, and time ela-ymeans associated with each of said contact means to maintain theconnection of the associated motor for a predetermined period of timeafter said contact means is deenergized to insure the effective brakingof the associated motor. a

' WILLIAM E. WRENN.

References Cited inthe file or this patent UNITED STATES PATENTS NumberName Date 1,970,389 Minneci Aug. 14, 1934 2,512,939 Aicher June 27, 1950

